Process of obtaining alum.



No. 712,226. Patented Oct. 28, I902. H. H. wma.

PROCESS OF OBTAINING ALum.

(Application filed Sept. 20, 1901.)

(No Mu del.)

#,Mw. W 2 W/TNESSES': I INVENTOI? 43 ATTORNEY 2 UNITED STATES PATENTOFFICE.

HERBERT H. WING, OF NEW BRIGHTON, NEW YORK.

PROCESS OF OBTAIINING ALUM.

SPECIFICATION forming part of Letters Patent No. 712,226, dated October28, 1902. Application filed September 20,1901. Serial No. 75,732. (Nospecimens.)

T0 otZZ whom it may concern:

Be it known that I, HERBERT H. WING, a citizen of the United States,residing at. New Brighton, in the county of Richmond and State of NewYork, have invented certain new and useful Improvements in Processes ofObtaining Alum; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

The object of my invention is to utilize sulfur fumes in the obtainingof chemical products in the place of other and more expensive chemicalswhich have hitherto always been used in the commercial production ofsuch chemical products and also to use sulfur fumes which are too diluteto use in the usual processes for the manufacture of sulfuric acid, &c.By my process I am also able to use sulfur fumes which are contaminatedwith air or with air and carbonic-acid gas or with sulfuric-acid gas. touse sulfur fumes which are a waste product and often a great nuisance,so that in many cases they have to be got rid of at great expense, thechemicals which I produce by the aid of such fumes are at presentproduced by expensive chemicals, among which sulfuric acid forms a largeitem of the cost of the materials used. The dilute sulfur fumes are bymy process converted into dilute sulfuric acid under such conditionsthat the oxidizing agent can be converted into an insoluble compound,and by so doing a further quantity of sulfuric acid is produced. Theinsoluble compound can then be separated from the acid liquor andregenerated to be used over again, and by repeating these operations anindefiniteamount of sulfur fumes can be converted into sulfuric acid bythe use of a definite and moderate quantity of oxidizing reagents.

The reagent which I use in the first step of my invention to generatethe first portion of sulfuric acid from the sulfur fumes is preferablythe sulfate of copper.

In general terms, my process consists in first passing sulfur fumescontaining sulfur dioxid and air with more or less of SO through aheated solution of copper sulfate, which-is maintained at suchtemperature preferably by use of hot sulfur fumes, but may be otherwiseheated, if preferred. The result of the Besides being able preferably bymeans of a filter-press.

continued passage of such fumes is the production of dilute sulfuricacid in the coppersulfate solution. WVhile the sulfur fumes are thuspassing through the copper-sulfate solution I preferably introduce intothis solution aluminium hydrate, either in the form of bauxite orrefined aluminium oxidor hydrate. By so doing the sulfuric acidgenerated from the sulfur fumes is neutralized as soon as produced,thereby utilizing any advantage that may be gained by the action ofnascent sulfuric acid. Besides this the copper sulfate is more activewith reference to the S0 when only a small amount of sulfuric acid ispresent. Time is also saved, as the alumina requires a certain amount oftime to be converted into sulfate, and the two reactions can in this waygo on simultaneously. When sufficient alumina has been converted intosulfate in a given quantity of liquid, the passage of the sulfur fumesis discontinued or preferably directed into a second absorbing-tank. Thesolution of the sulfates of aluminium and copper is then allowed tostand, and the insoluble impurities are settled or filtered out. I thenpass sulfureted-hydrogen gas through the solution, whereby the copper isprecipitated as copper sulfid and sulfuric acid is generated, while thealuminium sulfate is unacted upon. The copper sulfid is then separatedfrom the sulfate-of-alu minium solution, The copper sulfid is thenheated in a furnace or calcine'r, whereby itis converted into oxid andmore or less sulfate. The sulfur fumes mixed with air from thisoperation can .be utilized to convert the oXid thus produced intosulfate by passing them through a tank containing the oxid suspended inwater, forming first a sulfite and then the oxygen of the fumesoxidizing it to sulfate. The solution of aluminium sulfate which isseparated in the filter-press from the copper sulfid will contain theequivalent amount of sulfuric acid, according to'the equation- Thesulfuric acid is then neutralized with alumina or aluminium hydrate,thereby producing a further amount of sulfate of aluminium and at thesame time concentrating the solution.

The copper sulfate can also be separated from the aluminium-sulfatesolution by another method-viz., by electrolyzing the double sulfatesolution, producing copper at the cathode and liberating sulfuric acidat the anode. As it is injurious and also increases the cost ofdepositing the copper to allow the acid in the bath to accumulate, it ispreferable to withdraw continuously a por tion of the bath andneutralize the sulfuric acid therein with alumina or aluminium hydrateand then electrolyze these neutralized solutions until no furtherdeposit of copper can be obtained. The copper can be used to regeneratethe copper-sulfate solution by granulating it and bringing sulfur fumesin water in contact with it, or fresh quantities of roasted copper oresor mattes can be used to produce the copper-sulfate solution. Thesolution of aluminium sulfate which remains in each case after theseparation of the copper sulfate can then be concentrated and finallypoured out onto a floor to solidify, as is ordinarily done to make thealum cake or concentrated alum, as it is commercially called. Instead ofmaking the simple sulfate of aluminium from the dilute solution thusobtained it will require less evaporation to make a potash alum byadding to the solution of sulfate of aluminium the required amount ofsulfate of potassium to produce the compound AlK(SO 12H O, which is thenconcentrated and allowed to crystallize in tanks.

To carry out my process of utilizing sulfur fumes as above described,avariety of difierout forms of apparatus may be used. In the annexeddrawings I have shown a form of apparatus which is adapted for suchwork.

Figure 1 represents in elevation and partial section the apparatus forproducing the aluminium sulfate. Fig. 2 representsin sectional elevationa common reverberatory furnace, in which the copper sulfid may beconverted into sulfate.

In the drawings, X represents a source from which fumes containingsulfur dioxid may be obtained and may be a smeltingfurnace, ore-roaster,or any apparatus from which fumes containing sulfur dioxid can beobtained.

A represents a dust-collecting chamber for settling out any dust carriedby the fumes.

T T represent pipes which convey the fumes to the absorbing apparatus L,which consists of a tank provided with means, as E E, for agitating thecontents and mechanism G for operating the agitators E E.

e is a hopper with a valve 6 H represents a filter-press which isconnected with the absorber L by the pipe Z. The pump I is used to forcethe contents of the tank L through the filter-press H.

0 represents a tank for crystallizing out the alum.

D is a tank for producing sulfureted-hydrogen gas, and K is theoutlet-pipe for conducting the H 8 gas into the absorber L.

J is a furnace or calciner used to convert the copper sulfid into oxidand sulfate, the sulfur fumes from the same leading into an absorbersimilar to L, in which the mixed oXid and sulfate are converted into acoppersulfate solution.

The method of operating the apparatus shown in the drawings consists infirst passing the sulfur fumes containing SO with some air and more orless SO from the source X through the dust-settling chamber A, thenthrough the pipes T T and the absorbing apparatus L, through which theyare drawn by means of the suction maintained by the suction-blower U,which is connected to the upper part of the absorber L by the pipe u.The absorbing apparatus L is nearly filled with a solution of coppersulfate, to which is added a quantity of aluminium hydrate, either inthe form of powdered bauxite or refined alumina or aluminium hydrate.The reaction between the copper sulfate and the sulfur fumes proceedsbetter when the solution is heated, and this can be accomplished byusing hot sulfur fumes, which will soon heat up the solution, or theheat can be increased by use of a steam-jacket or steam-coils within thetank. By continuing to pass the sulfur fumes through the absorber theyare converted into dilute sulfuric acid, which as soon as liberated actson the suspended aluminium hydrate, producing the sulfate of aluminium.The solution of the copper sulfate is thereby rendered most active, asthe accumulation of free sulfuric acid retards the reaction. From timeto time more ofthe aluminium compound is added to the absorber until anydesired strength of aluminium-sulfate solution is obtained. The sulfurgases are then directed into a second absorber. The solution is nowfiltered or the insolubleimpurities settled out, if there are any, andthe solution is pumped back into the absorber L. I then passsulfureted-hydrogen gas, generated in any usual wayin tank D,through thesolution,keeping it agitated continuously until all the copper isprecipitated as the sulfid, sulfuric acid being produced at the sametime, while the aluminium-sulfate solution is unacted upon. The contentsof absorber L are then pumped into the filter-press H, where thecopper-sulfid precipitate is held and the sulfate-of-aluminiu insolution passes through. The copper sulfid is then removed fromfilter-press and heated in the furnace J, where if the temperature isslowly raised a considerable amount of the sulfid is oxidized directlyinto sulfate, while the balance is obtained as oxid, and the sulfurfumes from the same are drawn through another absorber, like L, in whichthe mixed oxid and sulfate are added to the water, so that afterasufficient length of time the oxid is converted into sulfite and thenoxidized to sulfate, thus obtaininga regenerated coppersulfate solutionin which to make another quantity of sulfate of aluminium. Thesulfate-of-aluminium solution passing through the filter-press H isforced into the tank K,

IIO

where I add a further quantity of the aluminium compound to neutralizethe sulfuric acid which was generated by the precipitation of the coppersulfid by the sulfureted hydrogen. the aluminium-sulfate solution. Thesulfuric acid generated by the combination of the sulfureted hydrogenand the copper sulfate can be neutralized before the copper sulfid isfiltered by the addition of the alumina or aluminium hydrate orafterward, as above described, the only difference being in the relativeconvenience of the two methods. Instead of using sulfureted-hydrogen gasfor the separation of the copper-sulfate solution from thealuminium-sulfate solution as it is produced in the absorber L, I canelectrolyze the double sulfate solution, thus obtaining the pure copperat the cathode and liberating sulfuric acid at the anode. As it isinjurious to the copper and increases the cost of depositing the copperwhen too acid a bath is used, I preferably Withdraw continuously aportion of the bath and neutralize the sulfuric acid with alumina oraluminium hydrate and then continue the electrolysis of theseneutralized solutions until no further deposit of copper can beobtained. The copper may then be sold as electrolytic copper, or it canbe granulated and used by treating it with sulfur fumes in an absorber,like L, or by previously oxidizing it and then treating it with sulfurfumes in an absorber, like L, whereby a copper-sulfate solution can beregenerated in which to make another quantity of sulfate of aluminium.When the electrolytic copper is sold as such, roasted copper ore ormatte can be used to make up the copper-sulfate solution, thus efiectingthe electrolytic refining of the matte and obtaining the alum product inone process. The solution of aluminium sulfate, which is obtained ineither case free from any other products, is now concentrated byevaporating the water therefrom until such a concentration is obtainedthat the sulfate when poured out on a stone floor will become in a shorttime a hard mass, as is the usual practice. The

alum cake or concentrated alum as it is called, is then broken up orground and barreled ready for shipment.

Instead of making the simple sulfate of aluminium from the dilutesolution it will require less evaporation to make apotash alum, which iseasily done by adding anhydrous sulfate of potash to the sulfate ofaluminium in solution in the proper proportion to form the com poundAlK(SO 12H O,-whichis then concentrated tanks.

As the sulfate of aluminium is used at pres- .ent where the doublesulfate of potassium and aluminium could be used to a very large extent,the amount of the former manufactured being several times as large asthe latter, the term alumhas come to be applied, in the trade to thesulfate of aluminium, so

This increases the strength of p and allowed to crystallize in that theword alum has come to mean either the sulfate of aluminium or the doublesulfate of aluminium and potassium. As both varieties may be produced bymy process, I have used the word alum as a generic term embracing boththe single and double sulfate, as above described.

What I claim as my invention is 1. The herein-described process ofobtaining alum which consists in bringing sulfur fumes containing sulfurdioxid and air into contact with a solution containing sulfate ofcopper, thereby liberating sulfuric acid; neutralizing the sulfuric acidthus set free by the oxid or hydrate of aluminium, whereby the sulfateof aluminium is produced; then breaking up the copper compound byseparating the copper therefrom and leaving the sulfuric acid with whichit was combined in the solution; then neutralizing said acid by addingthe oxid or hydrate of aluminium, thereby obtaining a solutioncontaining substantially sulfate of aluminium only.

2. The herein-described process of obtaining alum which consists inbringing sulfur fumes containing sulfur dioxid and air into contact witha solution containing sulfate of copper and holding the oxid or hydrateof alu minium in suspension, whereby the sulfur dioxid in said fumes isconverted into sulfuric acid and sulfate of aluminium is produced; thenbreaking up the copper compound by separating the copper therefrom andleaving the sulfuric acid withwhich it was combined in the solution;then neutralizing said acid by adding the oxid or hydrate of aluminium,thereby obtaining a solution containing substantially sulfate ofaluminium only; then crystallizing out the alum from said solution.

3. The herein-described process of obtainin galu minium sulfate and aby-product which consists in bringing sulfur fumes containing sulfurdioxid and air into contact with a solution containing sulfate of copperand holding IIO the oxid or hydrate of aluminium in suspension, wherebythe sulfur dioxid in said fumes is converted into sulfuric acid andsulfate of aluminium is produced; then bringing sulfureted hydrogen intocontact with said solution, whereby copper sulfid and sulfuric acid areproduced; then separating the insoluble copper sulfid from the liquorcontaining the aluminium sulfate and free sulfuric acid; thenneutralizing said acid with the oxid or hydrate of aluminium; whereby asolution containing substantiallysulfate of aluminium is obtained.

4:. The herein-described process of obtainin g aluminium sulfate and aby-p'roduct which consists in bringing sulfur fumes' containing sulfurdioxid and air into contact with a solution containing sulfate of copperand hold ing the oxid or hydrate of aluminium in suspension, whereby thesulfur dioXid in said fumes is converted into sulfuric acid and sulfateof aluminium is produced; then bring-v ing sulfureted hydrogen intocontact with &

said solution whereby copper sulfid and sulfuric acid are produced; thenseparating the insoluble copper sulfid from the liquor containing thealuminium sulfate and free sulfuric acid; then neutralizing said acidwith the oxid or hydrate of aluminium; whereby a solution containingsubstantially sulfate of aluminium is obtained; then concentrating saidsoiution,whereby crystallized aluminium sulfate is obtained on coolingthe solution.

5. The herein-described process of obtain ing aluminium sulfate and aby-product which consists in bringing sulfur fumes containing sulfurdioxid and air into contact with a solution containing sulfate of copperand holding the hydrate or oxid of aluminium in suspension, whereby thesulfur dioxid in said fumes is converted into sulfuric acid and sulfateof aluminium is produced; then bringing sulfureted hydrogen into contactwith said solution, whereby copper sulfid and sulfuric acid areproduced; then neutralizing said acid with the maid or hydrate ofaluminium; then separating the insoluble copper sulfid from the liquor,whereby a solution containing the aluminium sulfate is obtained.

6. The herein-described process of obtaining aluminium sulfate and aby-product which consists in bringing sulfur fumes containing sulfurdioXid and air into contact with a solution containing sulfate of copperand holding the hydrate or oxid of aluminium in suspension, whereby thesulfur dioxid in said fumes is converted into sulfuric acid and sulfateof aluminium is produced; then bringing sulfureted hydrogen into contactwith said solution, whereby copper sulfid and sulfuric acid areproduced; then neutralizing said acid with the oxid or hydrate of aluminium; then separating the insoluble copper sulfid from the liquor,whereby a solution containing the aluminium sulfate is obtained; thenconcentrating said solution, whereby crystallized aluminium sulfate isobtained on cooling the solution.

7. The herein-described process of obtaining alum and a by-product whichconsists in bringing sulfur fumes containing sulfur dioxid and air intocontact with a solution containing sulfate of copper and holding theoxid orhydrate of aluminium in suspension whereby the sulfurdioxid insaid fumes is converted into sulfuric acid and sulfate of aluminium isproduced; then bringing sulfureted hydrogen into contact with saidsolution, whereby copper sulfid and sulfuric acid are produced; thenseparating the insoluble copper sulfid from the liquor containing thealuminium sulfate and free sulfuric acid; then neutralizing said acidwith the oxid or hydrate of aluminium, whereby a solution containingsubstantially only the sulfate of aluminium is obtained; then addingsufficient sulfate of potassium to said solution whereby the doublesulfate of potassium and aluminil um is obtained.

8. The herein-described process of obtaining alum and a by-product whichconsists in bringing sulfur fumes containing sulfur dioxid and air intocontact with a solution containing sulfate of copper and holding theoxid or hydrate of aluminium in suspension whereby the sulfur dioxidinsaid fumesis converted into sulfuric acid and sulfate of aluminium isproduced; then bringing sulfureted hydrogen into contact with saidsolution, whereby copper sulfid and sulfuric acid are produced; thenseparating the insoluble copper sulfid from the liquorcontaining thealuminium sulfate and free sulfuric acid; then neutralizing said acid'with the oXid or hydrate of aluminium, whereby a solution containingsubstantially only the sulfate of aluminium is obtained; then addingsufiicient sulfate of potassium to said solution whereby the doublesulfate of potassium and aluminium is obtained; then crystallizing outsaid alum from said solution.

9. The herein-described process of obtaining alum and a by-product whichconsists in bringing sulfur fumes containing sulfur dioxid and air intocontact with a solution containing sulfate of copper and holding theoxid or hydrate of aluminium in suspension,whereby the sulfur dioxid insaid fumes is converted into sulfuric acid and sulfate of aluminium isproduced; then bringingsulfureted hydrogen into contact with saidsolution, whereby copper sulfid and sulfuric acid are produced; thenneutralizing said acid with the oxid or hydrate of aluminium; thenseparating the insoluble copper sulfid from the liquor containing thealuminium sulfate; then adding sufficient sulfate of potassium to saidsolution whereby the double sulfate of potassium and aluminium isobtained.

10. The herein-described process of obtaining alum and a by-productwhich consists in bringing sulfur fumes containing sulfur dioxid and airinto contact with a solution containing sulfate of copper and holdingthe oxid or hydrate of aluminium in suspension,whereby the sulfurdioXidin said fumes is converted into sulfuric acid and sulfate of aluminiumis produced; then bringing sulfureted hydrogen into contact with saidsolution, whereby copper sulfid and sulfuric acid are produced; thenneutralizing said acid with the oXid or hydrate of aluminium; thenseparating the insoluble copper sulfid from the liquor containing thealuminium sulfate; then adding sufficient sulfate of potassium to saidsolution whereby the double sulfate of potassium and aluminium isobtained; and then crystallizing out said alum from said solution.

In testimony whereof I hereto aifix my signature in presence of twowitnesses.

HERBERT I-I. WING.

Witnesses:

GEO. I-I. GIBSON, ARTHUR MERWIN Ross.

